The present invention relates to distributed data processing systems and in particular to a central processor controlled data system for use with microcomputer controlled fluid dispensers which are continually polled by the processor and information exchanged therebetween over a common serial data link. A unique data/complementary data format insures the reception of valid information.
Insuring the accurate reception of data is of particular importance in many fields of information transmission and has become increasingly critical with high speed computer technology where each bit of information has significance. Therefore it is absolutely necessary that the receiver be furnished means for checking each bit of data received to quarantee its validity. The dispensing of liquid fuels is no exception, where government standards and economy of operation demand virtually error free monitoring and control of the volume and cost of fuel dispensed.
The rapidly escalating prices of petroleum based fuels has seen a concomitant increase in the number of self-service dispensing stations. A need has therefore arisen for increasingly efficient fuel dispensing systems. It has become necessary to provide the customer and service station operator with a dispensing system which can rapidly accomodate fluctuating prices and money or volume dispensing limitations. Further, continuous monitoring and control of dispensing operations must be accomplished with the least supervisory personnel possible to best hold down rising costs and prices.
Heretofore, numerous hardwired electronic dispensing systems have been utilized. To update such systems to a central control has required complete rewiring of service stations at great expense and inconvenience. Moreover, in most cases the central console has been a mere slaved display allowing the station operator to do little more than reset a dispenser and monitor the end result. Alternatively, the central console itself has contained all of the computation circuitry of the system while the dispenser itself merely displays to the customer what the console has computed. In the latter case, the failure of the console will effectively close down all dispensing operations at the station. Still further, the nature of such system precludes the addition thereto of peripheral equipment such as ticket printers, cash registers etc. without extensive circuit redesign.
The recent advances in microprocessor and microcomputer technology have allowed an increase in the flexibility of design of these dispensing systems but, as with all electronic data systems, they remain susceptible to the introduction of spurious signals due to the numerous interconnecting control lines and electrical equipment located in a service station environment such as has been experienced in prior systems.
It is therefore highly desirable to provide an improved data processing system and method.
It is therefore highly desirable to provide a data processing system and method which insures the accurate reception of data between a transmitter and receiver.
It is also highly desirable to provide a data processing system and method which insures the accurate reception of data in a fuel dispensing system.
It is also highly desirable to provide a data processing system and method which has great flexibility in the establishing of various fluctuating, dispensing parameters.
It is also highly desirable to provide a data processing system and method which has a central console control which can supervise and monitor a dispensing operation while nonetheless allowing the dispensers to operate independently of the console in the event of its failure or desired manual dispensing operation.
It is also highly desirable to provide a data processing system and method which allows the addition of various future dispensing microcomputers thereto, without system redesign while ensuing the accurate transmission and reception of data to and from such equipment.